Combination process for the catalytic hydrodesulfurization and reforming of hydrocarbon mixtures



Jan. 1, 1952 STINE 2,580,478

COMBINATION PRQCESS FOR THE CATALYTIC HYDRODESULFURIZATIQN AND REFORMING OF HYDROCARBON MIXTURES Filed May 28, 1949 VIRGIN NAPHTHA VIRGIN GAS OIL REFORMING (INCLUDING HYDROFORMING) REFORMED NAPHTHA AND 3 BYPRODUCT GAS CONSISTING 3 OF H AND GASEOUS HYDRO- m CARBONS 8 COOL To g AMBIENT TEMPERATURE Z l E REFORMED BYPRODUCT g NAPHTHA GAS E.

BYPRODUCT GAS PURIFICATION BY ABSORPTION 0F GASEOUS HYDROCARBONS AT AMBIENT TEMPERATURE HYDROGEN ENRICHED GAS i GAS OIL PLUS HYDRODESULFURIZATION 2' BsoRaEI), GASEOUS g HYDROCARBONS HOT HEAT TO DESORB I H s ABSORBER GASEOUS HYDROCARBONS GASEOUS HYDROCARBONS HYDRODESULFURIZED T LIGHT s OCK FR CTION FRAcTIoNATIoN A HEAVY FRACTION (OPTIONAL) JNVENTQR.

HARRISON M. STI NE BY I W I! I, I %w HIS ATT RNEYs Patented Jan. 1, 1952 COMBINATION PROCESS FOR THE CATA- LYTIC HYDRODE SULFURIZATION AND RE- FORMING OF HYDROCARBON MIXTURES Harrison M. Stine, East Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Application May 28, 1949, Serial No. 96,051

4 Claims. (or; 190-24) "This invention relates to a process for the production of gasoline having a higher octane number from virgin naphthas and the like hydrocarbon mixtures by reforming, and for the production of a hydrodesuliurized gas oil wherein a gas oil is used to purify by-product gas from a catalytic reforming or hydroforming step by removing gaseous hydrocarbons from the byproduct gas, then separated and heated to drive out the absorbed gaseous hydrocarbons, and then subjected to a hydrodesulfurizati'on treatment in the presence of the scrubbed by-product gas to produce hydrodesulfurized gas oil. If desired, the hydrodesulfurized gas oil may be separated into a heavy fraction and a lighter naphtha fraction, and the naphtha fraction may be subjected to the reforming treatment to produce the improved gasoline and by-product gas which is used in the process.

In catalytic reforming by any of the conventional processes, a by-product gas is obtained which contains hydrogen and also normally gaseous hydrocarbons. This gas may be used as a source of hydrogen for hydrodesulfurization, or in the reforming. However, the gaseous hydrocarbon diluents therein are objectionable, and must be brought to a relatively low proportion. Especially is this so since in a continuous process the hydrogen is used up and the lower hydrocarbons accumulate. Thus it is necessary to separate the hydrocarbons from the hydrogen in a-continuous process.

After the reforming treatment, the treated stock is cooled to ambient temperatures such as about 80 F., and the gasoline fraction having the A marked conservation of energy is achieved in accordance with the invention by combining the two treatments so that the gas oil feed stock to be desuliurized is used as the scrubbing liquid for absorbing the gaseous hydrocarbons from re-.

forming by-product gas and leave a hydrogen enrichedgas, and is then heated (l) to drive all the absorbed gaseous hydrocarbons and (2) to raise the gas oil feed stock to a desirable hydrodesulfurization temperature.

The catalytic reforming is carried out in accordance with known procedures. By "reforming is meant a process of treating a stock at any elevated temperature in the presence of a catalyst to dehydrogenate and/or aromatize the straight chain hydrocarbons and naphthenes in the presence or obsence of added hydrogen. When the process is carried out in the presence of added hydrogen, it is commonly called hydroforming. Any reforming catalyst may be used under any reforming conditions. For example, one such catalyst is of the gel type, containing from 18 to 30 mol percent of chromium oxide (calculated as CrzOa) and the remainder aluminum oxide (calculated as A1203). The pressure may be in the range of 25 to 500 lbs. per square inch gauge, the temperature in the range of 800 to 1200 F., and the flow rate in the range of 0.1 to 10 liquid volumes of hydrocarbon per volume of catalyst per hour. Other catalysts of a the class known as aromatizing catalysts may be improved octane rating is separated from the byperature. i

used; generally these involve an oxide of a metal of the fifth and sixth periodic group, in an amount in the range of 5 to 50 mol percent with the balance being a refractoryo'xide such as alumina and/or silica or the like.

The hydrodesulfurization treatment is carried out in accordance with known procedures inthe presence of a hydrodesulfurizing catalyst. Any hydrodcsulfurizing catalyst and any hydrodesulfurizing conditions may be used although these always involve high temperatures. The process is one of reacting added hydrogen to convert the sulfur compound in the stock to gaseous sulfur compounds, generally Has. A typical catalyst of this type is cobalt oxide-molybdena-alumina. Another is a chromia-molybdena-alumina catalyst known in the art. Gas 011 or the like stocks containing from about 1 to about 6.5% by weight of sulfur in the form of organic sulfur compounds,

are treated to reduce the amount of sulfur therein by formation of hydrogen sulfide. The stock may be either in the liquid phase or in the gaseous phase, or mixtures thereof. The treatment may be at a temperature in the range of 500 to 1050 F., and the pressure in the range of 25 to 1000 lbs. per square inch gauge. The feed rate of the hydrocarbon stock to the catalyst may be in the range of 0.5 to liquid volumes per bulk volumeof catalyst per hour. 7

The attached drawing is a schematic flow diagram illustrating the generic aspects of the invention. In order to facilitate a further under.-

standing of the invention, the following specific embodiments are included for illustrative pursposes and not necessarily as liniitationsofthe About 12,500 barrels per stream day of virgin" gas oil containing 2.0% sulfur, is passed downwardly into a gas scrubber at ambient'temperature, countercurrent to 3,000,000 cubic feet-per stream day of by-productgas, at about 80 F. and at about 350 lbs. per square inch gauge, passed upwardlythrough the scrubber. The gas oil plus absorbed gaseous hydrocarbonsis then separated andlpassed to a heater at a lower pressure. Any temperature and pressure may be used which will accolrnplish the. desorption. Generally a tern-1 perature of 250? up to .;the hydrodesulfurizing temperature maybeflusedwith alow pressure of from ;0 to .several atmospheres In the specific example it is brought. toatemperature of about 450 F.,..at apressure ,ofiabout. onelatmosphere, and .600,000 -cubicfeet perstreamday of the gaseous hydrocarbons are drivenoif- The gas oil is then fed .into. a .hydrodesulfurization. unit, containing. a .cobalt. oxideemolyb dena-alumina catalyst,.at.750. F.,,300 p. s. i.,.1.0 v./v./hr., together with..2,40'0,000 cubic feet .lperstream day of the scrubbed or H2 enriched gas... 'I'hesulfurcontent of theoil, in the form of. organic sulfunisreducedto 0.25%..by weight sulfur About. 5,000 barrelsper stream day of virgin naphthais fed into ,a reforming .unit, containing a=30 mol percent alumina-.20 moi percent chromia catalyst, at 950 F., 25.-p..s.i.,-l.0 v./v./hr., with SO-minutes-on-stream. Nohydrogen is fed to the 7 unit... The treated material isthen. cooled to 80 Faandrtheliquid phase-is drawn off. It consists of 3600-barrels per streamday of 80 ASTM O. N. gasoline..' The Joy-product gas-is separated into twor-parts. 4,000,000scubicfeet-per stream day cycled, or maybe removed therefrom by a separatescrubbin .treatment,.-e. gnby aqueous caustic, orrby-the so-called Girbotol process. If the H28 is not otherwise removed, it .comes out with the gasloil, if the latter is properly cooled, and

canberdrivenfloff vortopped fromthe gas oil.v

If .desired, the gas oil may containthe naphtha so-that-thetreated gas oil fraction maybe passed to.a.,fractionating column, wherein. it is separated intowa heavy or. higher. boiling-fraction. .and a lighter fraction which is fed to the reformer. In

4 such an embodiment the desorption temperature is adjusted downwardly.

The product of this example is of desirable quality and is obtained in good yield.

The following are the material inspections:

Gas oil feed stock A. P. 1., 60 F r 27 Per cent sulfur 2.0 Anilinepoint .F.. 161.5 Avg. mol..;wt 293 Engler distillation range:

V "F. 5%@ (volume) 1-- 550 10;" V 569 30 610 50...- 651 696 751 Virgin naphtha fraction A.,P. 1., 60F 56 Engler distillation range V 1"- 5% (volume)' 194 10;- 20B 30 243 50 2'70 Reformer ,byrproduct gas 7 Per centlvolixme) H2"; 69 CH 1 02m- I 7 CsHs 6 C-iH'm 3 CsHis'- 2 H scrubbed reformer by-productgas Per cent (volume) Hz- 30.5 CH4 13.0 C2He 4.5 CsHs 2.0 C4Hm 0 C5H12 0 EXAMPLE 2 In'this example the reformingis carried out by the so'-calledhydroforming, in which-the treatment is carriedout in the presenceof added hydrogeni About 12,500 barrels .per streamdaypf virgin gas oilfh'avinga sulfur vcontent of 2.0%, is, passed downwardly into ascrubber unit at ambient tern:

perature, countercurrent to,l6,500,000 cubicfeet cobalt oxidermolybdena-alumina.. catalyst at 2,500,000.0ubic feet per stream daypf the scrubbed.

or 1H2 .ienriched .gas. Thetsulfuricontent ;of;the,

oil, in the form of organic sulfur, is reduccdtto- 0.25% by weight sulfur.

About 5,000 barrels per stream day of virgin naphtha is fed into a hydroforming unit containing the above described alumina-chromia catalyst, at 980 F., 1.0 v./v./hr. and 75 p. s. i., running 2 hours on-stream time. The remainder of the scrubbed or H2 enriched by-product gas, about 13,200,000 cubic feet per stream day, is also fed or recycled into this unit. The hydroformed product is cooled to about 80 F., and the liquid is separated therefrom. It consists of about 4200 barrels per stream day of 78 ASTM O. N. gasoline. The remainder is about 16,500,- 000 cubic feet per stream day of by-product gas at system pressure, indicating that about 3,300,- 000 cubic feet per stream day is formed during the hydroforming which is the amount removed in scrubbing and used in hydrodesulfurizing. The products of the example are obtained in good yield and are of good quality as indicated.

The gas oil may contain the naphtha, and if so, the desulfurized gas oil is then passed to a fractionator wherein it is separated into a light or naphtha fraction, e. g., boiling in the range of 200 to 400 F. which is fed to the hydroformer, and a heavy or higher boiling fraction. In such an embodiment the desorption temperature is similarly adjusted downwardly.

Material inspections or characteristics are as follows:

Gas oil API, 60 F 27 Per cent sulfur 2.0 Aniline point F 161.5 Avg. mol. wt 293 Engler distillation range:

F. 5% (volume) 550 569 30 610 50 651 70 696 90 751 Virgin naphtha fraction API, 60 F 56 Engler distillation range:

F. 5% (volume) 194 10 208 30 243 50 270 70 299 90 344 Hudroformed bzl-product aas Per cent (volume) H2 88 CH4 4 CzHc 3 Cal-Is 2 Gil-I10 2 CsHn 1 Scrubbed hydrojormed by-prod uct gas Per cent (volume) H2 90 CH4 4 CzHs 3 C3Ha 2 C4H1o 1 C5H1z 0 The process of the invention is operative with any hydrodesulfurization process using any of the known suitable catalysts, as well as with any known reforming process and catalyst. The essential requirements are that the reforming produce by-product gas containing hydrogen diluted with hydrocarbon material which can be absorbed by the hydrodesulfurization feed stock.

In view of the foregoing disclosures, variations or modifications thereof will be apparent to those skilled in the art and the invention contemplates all such variations and modifications except as do not come within the scope of the appended claims.

Iclaim:

1. A process of treating naphtha and gas oil fractions, which comprises reforming naphtha to form gasoline of higher octane number and produce a by-product gas containing hydrogen and gaseous hydrocarbons, scrubbing said reformed by-product gas at an ambient temperature with gas oil feed stock to remove gaseous hydrocarbons from the gas and to provide a hydrogen enriched by-product gas, separating and heating the gas oil feed stock to drive off absorbed gaseous hydrocarbons, and then hydrodesulfurizing the heated gas oil feed. stock with said hydrogen enriched by-product gas.

2. The process of claim 1 wherein the reforming is hydroforming and is carried out in the presence of a part of the scrubbed by-product gas.

3. The process of claim 1 in which the naphtha and gas oil is in a single fraction and the desulfurized stock is fractionated and the naphtha fraction is reformed.

4. The process of claim 1 wherein the hydrodesulfurization is carried out with the scrubbed by-product gas and in the presence of cobalt molybdate on aluminum catalyst, at; 750 F., a 300 p. s. i., and 1.0 v./v./hr., and the reforming is carried out in the presence of mol per cent alumina-20 mol per cent chromia catalyst at 950 F., 25 p. s. i. and 1.0 v./v./hr.

HARRISON M. STINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,315,144 Watson Mar. 30, 1943 2,349,160 Frey et a1 May 16, 1944 2,463,741 Byrns Mar. 8, 1949 FOREIGN PATENTS Number Country Date 285,668 Great Britain Feb. 23, 1928 

1. A PROCESS OF TREATING NAPHTHA AND GAS OIL FRACTIONS, WHICH COMPRISES REFORMING NAPHTHA TO FORM GASOLINE OF HIGHER OCTANE NUMBER AND PRODUCE A BY-PRODUCT GAS CONTAINING HYDROGEN AND GASEOUS HYDROCARBONS, SCRUBBING SAID REFORMED BY-PRODUCT GAS AT AN AMBIENT TEMPERATURE WITH GAS OIL FEED STOCK TO REMOVE GASEOUS HYDROCARBONS FROM THE GAS AND TO PROVIDE A HYDROGEN ENRICHED BY-PRODUCT GAS, SEPARATING AND HEATING THE GAS OIL FEED STOCK TO DRIVE OFF ABSORBED GASEOUS HYDROCARBONS, AND THEN HYDRODESULFURIZING THE HEATED GAS OIL FEED STOCK WITH SAID HYDROGEN ENRICHED BY-PRODUCT GAS. 